Quinine--a tonic too bitter for hemodialysis-associated muscle cramps?

Hemodialysis patients are susceptible to muscle cramps, both during dialysis sessions as well as in the interdialytic interval. These cramps are often very painful, disruptive to the dialysis treatment, and adversely affect quality of life. There is no well-defined means of preventing or treating these cramps. Quinine sulfate has been used with apparent success in some patients, but the Food and Drug Administration recently ordered the cessation of marketing of unapproved quinine formulations and advised consumers to avoid "off-label" use of quinine for cramps. We review the causes and consequences of hemodialysis-associated cramps, and discuss possible preventive measures and treatments.